Fault under reactor to be checked once more

The Nuclear Regulation Authority may send experts to the Tsuruga nuclear power plant in Fukui Prefecture to further study a geologic fault that the NRA determined in May to be active, sources said.

The NRA commissioners will discuss the issue during their regular meeting Wednesday. The purpose of the on-site investigation would be to check whether there are grounds to revise the NRA’s judgment on the fault running beneath reactor No. 2.

If plant operator Japan Atomic Power Co. can’t convince the panel members that the fault will not move in the future, the utility may have to scrap the reactor.

Japan Atomic Power says a new investigation that it carried out has shown that the fault is not active. But its explanations have not changed largely from May, indicating the NRA is unlikely to revise its conclusion.

The NRA determined in May that a zone of rock fragments called D-1 running directly beneath reactor 2 is an active fault based on the findings of a large-scale trench excavation.

The trench was created in the direction of where D-1 is expected to be running. The NRA said it can’t be disputed that one of the faults found in the trench, called “K,” moved in the last 120,000 to 130,000 years, which can be identified as active.

It said Fault K is linked with Fault D-1, thus concluding that D-1 is also active.

Japan Atomic Power said in July it hasn’t made any money from its electricity wholesale business as all three of its reactors remain offline. The firm is surviving on so-called basic fees from several regional utilities with which it has contracts to supply electricity.